Since the 3rd Generation Partnership Project Release7 (3GPP Release7) standard system is proposed, the policy and charging function is realized by a Policy and Charging Control (PCC) framework. The PCC framework is a function framework applicable to multiple access technologies, for example, the PCC framework is applicable to a Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN), an Enhanced Data Rate for GSM (Global System for Mobile Communication) Evolution (EDGE) radio access network, an Intelligent Wireless Local Area Network (I-WLAN) and an Evolved Packet System (EPS), etc.
The PCC mainly realizes two functions, that is, policy control function and charging function. FIG. 1 shows a schematic diagram of a PCC framework in existing Release-11; hereinafter, each logical function entity and the interface function thereof in the PCC framework shown in FIG. 1 are described. As shown in FIG. 1:
Application Function (AF) is configured to provide an access point of service application, wherein network resources used by the service application need to be processed with dynamical policy control. When parameter negotiation is conducted on a service plane, the AF transmits related service information to a Policy and Charging Rules Function (PCRF). If the service information is consistent with the policy of the PCRF, the PCRF accepts the negotiation; otherwise, the PCRF rejects the negotiation, and provides a service parameter acceptable by the PCRF during feedback; subsequently, the AF returns the parameter to User Equipment (UE), wherein the interface between the AF and the PCRF is an Rx interface.
The PCRF is the core of the PCC and is responsible for establishing policy and charging rules. The PCRF provides network control rules based on a service data flow, wherein the network control includes detection, gating control, Quality of Service (QoS) control of the service data flow, and charging based on the data flow. The PCRF sends the policy and charging rules established by the PCRF itself to a Policy and Charging Enforcement Function (PCEF) to execute, meanwhile, the PCRF needs to guarantee the consistency between the rules and the subscription information of a user. The basis for the PCRF to establish the policy and charging rules includes: receiving service related information from the AF, obtaining user subscription information of PCC related to policy control and charging from a Subscription Profile Repository (SPR), and obtaining bearer related network information from the PCEF.
The PCEF generally is located inside a Gate-Way (GW) and is used for enforcing the policy and charging rules established by the PCRF on a bearer plane. The PCEF performs detection on service data flows according to a service data flow filter in the rules sent by the PCRF, thereby enforcing the policy and charging rules established by the PCRF for the service data flow. When a bearer is established, the PCEF allocates resources according to the rules sent by the PCRF and performs gating control according to the information provided by the AF; meanwhile, the PCEF triggers the report of events occurring on a bearer network according to an event subscribed by the PCRF; according to the charging rules sent by the PCRF, the PCEF executes a corresponding service data flow charging operation, wherein the charging can be online charging or offline charging. If in the online charging, the PCEF needs to perform credit management together with an Online Charging System (OCS); if in the offline charging, the PCEF exchanges related charging information with an Offline Charging System (OFCS). The interface between the PCEF and the PCRF is a Gx interface; the interface between the PCEF and the OCS is a Gy interface; and the interface between the PCEF and the OFCS is a Gz interface. The PCEF also can have a Traffic Detection Function (TDF). The PCEF can perform application detection and policy enforcement (for example, gating control, redirection and bandwidth limit) according to local configurations or PCC rules containing an Application Detection and Control (ADC) policy distributed by the PCRF. The PCEF generally is located on a network gateway, such as, a Packet Data Network Gateway (PDN-GW) of EPS, a General Packet Radio Service (GPRS) Gateway Support Node (GGSN), and a Packet Data Gateway (PDG) in an Interworking Wireless Local Area Network (I-WLAN).
The TDF also can be deployed separately; at this time, the TDF is connected with the PCRF through an Sd interface; the TDF can perform application detection and policy enforcement according to an ADC rule preconfigured or distributed by the PCRF.
Bearer Binding and Event Reporting Function (BBERF) generally is located in an access network gateway. For example, when UE accesses the EPS through an Evolved UTRAN (E-UTRAN) and Proxy Mobile Internet Protocol version6 (PMIPv6) is applied between a Serving Gateway (S-GW) and a Packet Data Network-Gateway (P-GW), the BBERF exists in the S-GW. When UE accesses the EPS through an untrusted non-3GPP access network, the BBERF also exists in the untrusted non-3GPP access gateway.
The SPR stores the user subscription information of PCC related to policy control and charging. The interface between the SPR and the PCRF is an Sp interface.
The OCS and the PCEF together accomplish the user credit control and management in the online charging mode.
The OFCS and the PCEF together accomplish the charging operation in the offline charging mode.
FIG. 2 shows a flowchart of establishing a TDF session between a TDF and a PCRF in an existing IP-CAN session process, in which the TDF applies a non-requested report mode. As shown in FIG. 2, the process specifically includes the following steps:
Step 201: during the process of UE requesting establishment of an IP-CAN session, a gateway where a PCEF is located receives an IP-CAN session establishment request message, wherein the IP-CAN session establishment request message carries a user Identifier (ID), and a PDN ID of the PDN network which the user requests to access;
Step 202: the PCEF sends a message of indication of IP-CAN session establishment to the PCRF, and makes the message of indication of IP-CAN session establishment carry the user ID, the PDN ID and an IPv6 address prefix allocated for the UE;
Step 203: after determining that there is no subscription information of the user according to the user ID, the PCRF sends a subscription document request to an SPR and makes the subscription document request carry the user ID and the PDN ID;
Step 204: the SPR returns corresponding user subscription information (through a subscription document response) according to the user ID and the PDN ID;
Step 205: the PCRF makes a policy (including establishing PCC rules and event triggers) according to returned user subscription information, network policy, UE access information and the like;
Step 206: the PCRF sends an acknowledge IP-CAN session establishment message to the PCEF and makes the acknowledge IP-CAN session establishment message carry the PCC rules and event triggers;
Step 207: the PCEF installs the policy; the gateway where the PCEF is located returns an IP-CAN session establishment response to the UE and makes the IP-CAN session establishment response carry the IPv6 address prefix;
through the process shown in FIG. 2, the UE can construct an IPv6 address according to the IPv6 address prefix and access a service using the IPv6 address;
Step 208: the TDF finds a new IPv6 address (this IPv6 address is constructed by the UE according to the IPv6 address prefix in Step 207) when detecting traffic which pass through the TDF, then, the TDF sends a TDF session establishment message to the PCRF and makes the TDF session establishment message carry the new IPv6 address; and
Step 209: the PCRF associates the TDF session with the IP-CAN session according to the IPv6 address prefix obtained from the PCEF and the IPv6 address obtained from the TDF, and returns a TDF session establishment acknowledgement message to the TDF; the established TDF session corresponds to the IP-CAN session established by the UE.
Hereafter, the TDF performs application detection and control on uplink traffic, of which the source address is the new IPv6 address, and/or downlink traffic, of which the destination address is the new IPv6 address, according to the preconfigured ADC rule; and the TDF detects an appointed application (marked by Application ID) in the preconfigured application detection policy. The TDF sends an application detection report to the PCRF via the TDF session established in Step 208 and Step 209, carrying the detected Application ID and an optional event trigger which takes Start of application traffic detection and Stop of application traffic detection as a value; if the PCRF subscribes to the event trigger Start of application traffic detection and Stop of application traffic detection with the TDF, the TDF probably would provide Service Data Flow Description for the PCRF. Then, the PCRF makes a policy, makes or updates PCC rules according to the Application ID and the Service Data Flow Description (if reported) reported by the TDF, and provides the policy and rules to the PCEF.
However, the existing technology does not take dual-stack into account, that is, one same IP-CAN session has an IPv4 address and an IPv6 address simultaneously. After the process shown in FIG. 2, if the gateway where the PCEF is located or another external network element further allocates an IPv4 address according to a request from UE and the UE accesses a service using the IPv4 address, at this time, the TDF finds a new IPv4 address, initiates establishment of a TDF session and reports an application detection result to the PCRF via the established TDF session.
This could cause a result that an IP-CAN session has two TDF sessions simultaneously, and the service detection for the same one IP-CAN session needs to be reported via different TDF sessions. Thus, resources are wasted and signalling overhead is increased.
In addition, the standalone TDF supporting solicited application reporting mode will encounter this problem too; at this time, the process of establishing a TDF session, as shown in FIG. 3, includes the following steps:
Step 301: during the process of UE requesting establishment of an IP-CAN session, a gateway where the PCEF is located receives an IP-CAN session establishment request message, wherein the IP-CAN session establishment request message carries a user ID, and a PDN ID of the PDN network which the user requests to access;
Step 302: the PCEF sends a message of indication of IP-CAN session establishment to a PCRF, and makes the message of indication of IP-CAN session establishment carry the user ID, the PDN ID and an IPv6 address prefix allocated for the UE;
Step 303: after determining that there is no subscription information of the user according to the user ID, the PCRF sends a subscription document request to an SPR and makes the subscription document request carry the user ID and the PDN ID;
Step 304: the SPR returns corresponding user subscription information (through a subscription document response) according to the user ID and the PDN ID; the user subscription information includes a user document configuration, instructing to activate application detection and control;
Step 305: the PCRF makes a policy (including establishing PCC rules and optional event triggers) according to returned user subscription information, network policy, UE access information and the like; in this step, since the user subscription information includes the user document configuration, the PCRF also needs to establish an ADC rule, wherein the ADC rule includes: setting an Application ID used for indicating the application needed to be detected by the PCEF, setting an event trigger which takes Start of application traffic detection and Stop of application traffic detection as a value, and setting possible enforcement policy corresponding to each detected application, including gating control, maximum bandwidth and redirection;
Step 306: the PCRF sends a TDF session establishment request to the TDF, and makes the TDF session establishment request message carry the IPv6 address prefix, the ADC rule and the optional event trigger, wherein the event trigger takes Start of application traffic detection and Stop of application traffic detection as a value;
Step 307: the TDF enforces the policy, installs or activates the ADC rule and the event trigger;
Step 308: the TDF returns a TDF session establishment acknowledgement message to the PCRF;
Step 309: the PCRF sends an acknowledge IP-CAN session establishment message to the PCEF, and makes the acknowledge IP-CAN session establishment message carry the PCC rules and the event trigger; and
Step 310: the PCEF installs the policy; the gateway where the PCEF is located returns an IP-CAN session establishment response to the UE, and makes the IP-CAN session establishment response carry the IPv6 address prefix.
Through the process shown in FIG. 3, the UE can construct an IPv6 address according to the IPv6 address prefix, and access a service using the IPv6 address. The established TDF session corresponds to the IP-CAN session established by the UE.
Hereafter, the TDF performs application detection and control on uplink traffic, of which the source address is the IPv6 address (which can be uniquely determined by the TDF according to the IPv6 address prefix obtained from the PCRF), and/or downlink traffic, of which the destination address is the IPv6 address, according to the ADC rule distributed by the PCRF. When the TDF detects an application corresponding to the Application ID and the PCRF subscribes to Start of application traffic detection and Stop of application traffic detection, the TDF sends an application detection report to the PCRF via the TDF session established in Step 306 to Step 308, carrying the detected Application ID and the event trigger which takes Start of application traffic detection as a value; then, the PCRF makes a policy, sets or updates the enforcement policy (for example, gating control, maximum bandwidth and redirection) according to the reported Application ID, establishes or updates PCC rules and provides the rules to the PCEF.
After the process shown in FIG. 3, if the gateway where the PCEF is located or another external network element further allocates an IPv4 address according to a request from the UE, and the UE accesses a service using the IPv4 address, at this time, the TDF finds a traffic of a new IPv4 address when detecting the traffic; since the TDF is not notified to detect the traffic of the IPv4 address and has no corresponding ADC rule used for detecting the service flow, the TDF will not detect the traffic. At this time, the PCRF can initiate a request of establishing a new TDF session, subsequently causing that an IP-CAN session has two TDF sessions simultaneously, and the service detection for the same one IP-CAN session needs to be reported via different TDF sessions. Thus, resources are wasted and signalling overhead is increased.